Reflow protection

ABSTRACT

Devices and techniques to reduce corruption of received data during assembly are disclosed herein. A memory device can perform operations to store received data, including preloaded data, in a first mode until the received data exceeds a threshold amount, and to transition from the first mode to a second mode after the received data exceeds the threshold amount.

PRIORITY APPLICATION

This application is a continuation of U.S. application Ser. No.15/689,989, filed Aug. 29, 2017, which is incorporated herein byreference in its entirety.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits in computers or other electronic devices. There aremany different types of memory, including volatile and non-volatilememory.

Volatile memory requires power to maintain its data, and includesrandom-access memory (RAM), dynamic random-access memory (DRAM), orsynchronous dynamic random-access memory (SDRAM), among others.

Non-volatile memory can retain stored data when not powered, andincludes flash memory, read-only memory (ROM), electrically erasableprogrammable ROM (EPROM), static RAM (SRAM), erasable programmable ROM(EPROM), resistance variable memory, such as phase-change random-accessmemory (PCRAM), resistive random-access memory (RRAM), magnetoresistiverandom-access memory (MRAM), or 3D XPoint™ memory, among others.

Flash memory is utilized as non-volatile memory for a wide range ofelectronic applications. Flash memory devices typically include one ormore groups of one-transistor, floating gate or charge trap memory cellsthat allow for high memory densities, high reliability, and low powerconsumption.

Two common types of flash memory array architectures include NAND andNOR architectures, named after the logic form in which the basic memorycell configuration of each is arranged. The memory cells of the memoryarray are typically arranged in a matrix. In an example, the gates ofeach floating gate memory cell in a row of the array are coupled to anaccess line (e.g., a word line). In a NOR architecture, the drains ofeach memory cell in a column of the array are coupled to a data line(e.g., a bit line). In a NAND architecture, the drains of each memorycell in a string of the array are coupled together in series, source todrain, between a source line and a bit line.

Both NOR and NAND architecture semiconductor memory arrays are accessedthrough decoders that activate specific memory cells by selecting theword line coupled to their gates. In a NOR architecture semiconductormemory array, once activated, the selected memory cells place their datavalues on bit lines, causing different currents to flow depending on thestate at which a particular cell is programmed. In a NAND architecturesemiconductor memory array, a high bias voltage is applied to adrain-side select gate (SGD) line. Word lines coupled to the gates ofthe unselected memory cells of each group are driven at a specified passvoltage (e.g., Vpass) to operate the unselected memory cells of eachgroup as pass transistors (e.g., to pass current in a manner that isunrestricted by their stored data values). Current then flows from thesource line to the bit line through each series coupled group,restricted only by the selected memory cells of each group, placingcurrent encoded data values of selected memory cells on the bit lines.

Traditional memory arrays are two-dimensional (2D) structures arrangedon a surface of a semiconductor substrate. To increase memory capacityfor a given area, and to decrease cost, the size of the individualmemory cells has decreased. However, there is a technological limit tothe reduction in size of the individual memory cells, and thus, to thememory density of 2D memory arrays. In response, three-dimensional (3D)memory structures, such as 3D NAND architecture semiconductor memorydevices, are being developed to further increase memory density andlower memory cost.

Such 3D NAND devices often include strings of storage cells, coupled inseries (e.g., drain to source), between one or more source-side selectgates (SGSs) proximate a source, and one or more drain-side select gates(SGDs) proximate a bit line. In an example, the SGSs or the SGDs caninclude one or more field-effect transistors (FETs) or metal-oxidesemiconductor (MOS) structure devices, etc. In some examples, thestrings will extend vertically, through multiple vertically spaced tierscontaining respective word lines. A semiconductor structure (e.g., apolysilicon structure) may extend adjacent a string of storage cells toform a channel for the storages cells of the string. In the example of avertical string, the polysilicon structure may be in the form of avertically extending pillar. In some examples the string may be“folded,” and thus arranged relative to a U-shaped pillar. In otherexamples, multiple vertical structures may be stacked upon one anotherto form stacked arrays of storage cell strings.

Memory arrays or devices can be combined together to form a storagevolume of a memory system, such as a solid-state drive (SSD), aUniversal Flash Storage (UFS™) device, a MultiMediaCard (MMC)solid-state storage device, an embedded MMC device (eMMC™), etc. An SSDcan be used as, among other things, the main storage device of acomputer, having advantages over traditional hard drives with movingparts with respect to, for example, performance, size, weight,ruggedness, operating temperature range, and power consumption. Forexample, SSDs can have reduced seek time, latency, or other delayassociated with magnetic disk drives (e.g., electromechanical, etc.).SSDs use non-volatile memory cells, such as flash memory cells toobviate internal battery supply requirements, thus allowing the drive tobe more versatile and compact.

An SSD can include a number of memory devices, including a number ofdies or logical units (e.g., logical unit numbers or LUNs), and caninclude one or more processors or other controllers performing logicfunctions required to operate the memory devices or interface withexternal systems. Such SSDs may include one or more flash memory die,including a number of memory arrays and peripheral circuitry thereon.The flash memory arrays can include a number of blocks of memory cellsorganized into a number of physical pages. In many examples, the SSDswill also include DRAM or SRAM (or other forms of memory die or othermemory structures). The SSD can receive commands from a host inassociation with memory operations, such as read or write operations totransfer data (e.g., user data and associated integrity data, such aserror data and address data, etc.) between the memory devices and thehost, or erase operations to erase data from the memory devices.

Each memory cell in a memory array can be programmed individually orcollectively to one or a number of programmed states. For example, asingle-level cell (SLC) can represent one of two programmed states(e.g., 1 or 0), representing one bit of data. In other examples, memorycells can represent one of more than two programmed states, allowing themanufacture of higher density memories without increasing the number ofmemory cells, as each cell can represent more than one binary digit(e.g., more than one bit). Such cells can be referred to as multi-statememory cells, multi-digit cells, or multi-level cells (MLCs). In certainexamples, MLC can refer to a memory cell that can store two bits of dataper cell (e.g., one of four programmed states), a triple-level cell(TLC) can refer to a memory cell that can store three bits of data percell (e.g., one of eight programmed states), and a quad-level cell (QLC)can store four bits of data per cell. MLC is used herein in its broadercontext, to can refer to any memory cell that can store more than onebit of data per cell (i.e., that can represent more than two programmedstates).

Memory cells may be subject to high temperatures during assembly of amemory device, assembly of an electronic device or printed circuit board(PCB) including the memory device, or other production processassociated with the memory cells. For example, the memory device can beattached to a PCB using an infrared (IR) reflow operation, havingtemperatures that may exceed 240° C. Exposing memory cells to hightemperatures can change the threshold voltage of the memory cells,causing errors in stored data. SLC memory cells typically have greaterthreshold temperature margins than MLC memory cells (e.g., MLC, TLC, QLCmemory cells, etc.). Accordingly, data preloaded onto memory cells priorto some application of high temperature, such as firmware loaded onto amemory device prior to assembly, can be stored on the memory cells asSLC data.

Certain memory devices have separate SLC and MLC portions, such asdisclosed in Mekhanik et al. U.S. Pat. No. 9,229,806 (herein the '806patent), assigned to SanDisk Technologies LLC. The '806 patent detectsan error rate in the memory device. When the error rate is greater thana threshold, the IR reflow process is assumed complete, and preloadeddata can be moved from the SLC portion of the memory device to an MLCportion of the memory device. However, such method requires detection oferror rates in memory and comparison to a threshold while the error rateis below such threshold, as well as required, separate SLC and MLCportions of memory.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numeralsmay describe similar components in different views. Like numerals havingdifferent letter suffixes may represent different instances of similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

FIG. 1 illustrates an example of an environment including a memorydevice.

FIGS. 2-3 illustrate schematic diagrams of an example of a 3D NANDarchitecture semiconductor memory array.

FIG. 4 illustrates an example block diagram of a memory module.

FIGS. 5A-5B illustrate example charge distributions for single-level andmulti-level cells.

FIG. 6 illustrates an example block diagram of a memory device.

FIG. 7 illustrates an example method for managing a memory device.

FIG. 8 is a block diagram illustrating an example of a machine uponwhich one or more embodiments may be implemented.

DETAILED DESCRIPTION

The present inventors have recognized, among other things, robustprotection of temperature-vulnerable data on memory cells duringassembly or manufacture, in certain examples, without calculation oferror rates, without a comparison of calculated error rates to athreshold, without required, separate, physical SLC and MLC portions ofmemory, without receiving an indication of the size or amount oftemperature-vulnerable data prior to assembly or manufacture, withoutreceiving a separate indication that assembly or manufacture hasoccurred or completed, or without receiving a separate verification ofpreloaded data.

During manufacture or assembly, electronic parts are subject to hightemperatures, such as during molding or curing of materials, attachmentor mounting of one or more components to a board or another component,soldering, etc. For example, a memory device can include a number ofdies or logical units, as well as one or more memory controllers,processors, or other logical units and interfaces. In certain examples,the respective dies and memory controllers are manufactured separately,then assembled into the memory device. Assembly of the memory device caninclude a number of processes involving heat. Further, the memory devicecan be attached or included as a component of an electronic device.

In an example, the memory device can be attached to a board or othercontact of the electronic device (or other component) using heat, suchas reflow soldering (e.g., infrared (IR) reflow soldering). Duringreflow soldering of a memory device, a solder paste can be applied toareas (e.g., contacts) of the memory device requiring soldering (and notto areas not requiring soldering, such as using selective application ofsolder paste, or solder resist or a solder mask, etc.). Once the solderpaste is applied, the memory device can be placed in position forattachment, and heated. The reflow process may include a number of stepscarefully controlled to avoid thermal damage to the memory device,board, or other components. An example reflow process includes:preheating; thermal soak; reflow (e.g., causing the solder pate to meltand create solder joints); and cooling. In certain examples, a singlememory device may be subject to heating multiple times, either asredundant process steps to ensure connection, or as other components areattached to the memory device, board, or other component associated withthe memory device.

However, even if the physical components or packaging of the memorydevice are not damaged during reflow soldering, data stored on thememory device can be shifted (e.g., can leak) or become corrupted duringheating. Whereas erase/program cycles may cause distribution errors toflatten and widen, in certain examples, IR reflow may cause voltagedistribution of stored data to narrow (e.g., leak, shift left, etc.)from existing threshold voltages. Smaller gaps between thresholdvoltages (e.g., such as found in multi-level cells (MLC) in contrast tosingle-level cells (SLC)) are more susceptible to heat-related readerrors and data corruption.

Accordingly, data stored on a memory array prior to manufacture orassembly of a memory device including the memory array, or an electronicdevice including the memory device, may be subject to heat-relatedcorruption. In certain examples, memory cells in a memory array (e.g., aNAND memory array, a three-dimensional (3D) NAND memory array, etc.) canbe operated as single-level cells (SLC) or multi-level cells (MLC)(including two-level cells, triple-level cells (TLC), quad-level cells(QLC), etc.). In other examples, memory arrays can include a combinationof SLC and MLC, or can include different portions of a memory array(e.g., blocks, pages, die, etc.) dedicated as SLC or MLC. However, suchcombinations, in certain examples, may fail to fully utilize the storagecapabilities (e.g., capacity) of the memory array for given storedinformation or use conditions or scenarios.

In one example, data can be stored on the memory array in a single-levelor reflow-protection mode (e.g., as SLC), until a host device providesan indication (e.g., a flag, an instruction, etc.) to the memory devicethat reflow soldering, heating, or assembly of an electronic deviceincluding the host device including a memory device including the memoryarray is complete, and to transition operation of the memory device fromthe single-level or reflow-protection mode to a normal-operation ormulti-level mode (e.g., as MLC, TLC, QLC, a “normal” mode, etc.), suchas to more fully utilize the storage capability of the memory array. Forexample, the UFS 2.1 standard provides for Production State Awareness,where a first host device (e.g., a device configured to program one ormore memory arrays with information, such as preloaded data for anelectronic device) loads and verifies that preloaded data has beenwritten to the memory array prior to reflow, assembly, or manufacture ofa second host device. After verification, the host device notifies thememory device that loading is complete, where the memory device isexpected to undergo reflow or assembly, and then transition to normaloperation at the next write. However, if any data is written after thehost notifies that loading is complete, the drive can transition priorto reflow or assembly, and data can be corrupted. Further, somemanufacturers or users refuse to provide an indication to the memorydevice that preloaded data has been written, or that assembly iscomplete, or desire separate or redundant systems or methods.

Accordingly, the present inventors have recognized that certainconditions can be assumed for given use conditions, or information(e.g., preloaded data) can be received prior to assembly that can beused to fully utilize the storage capacity of the memory array, whileprotecting data stored during assembly, without receiving a separateindication of completed assembly. In certain examples, it can be assumedthat the memory device will undergo a certain number of power cyclesprior to final assembly, and the memory device can transition from thereflow-protection mode to the normal-operation mode after a number ofpower cycles (e.g., 3, 4, 5, or more or less, depending on themanufacturer, memory device, electronic device, typical use situations,etc.). In other examples, the threshold amount can include a ratio(e.g., a ration of MLC to SLC of 3:1, etc.), or one or more otherpre-set amounts. In certain examples, the MLC portion of the memoryarray can remain MLC, and the SLC portion of the memory array can remainSLC. Such configuration may reduce the capabilities of the memory array,but may be more robust in operation. If an instruction to write receiveddata in the reflow-protection mode would exceed the capacity of the SLCportion of the memory array, and error message can be returned, and thehost device can provide the instruction in normal-operation mode.

In other examples, a host device configured to provide preloaded data(e.g., a kernel, pre-loaded software or instructions, etc.) to thememory device prior to assembly can be different than the electronicdevice configured to include the memory device after assembly. Incertain examples, the memory device can transition from thereflow-protection mode to the normal-operation mode after receiving datafrom a device different than the host device that provided the preloadeddata. In an example, if a command descriptor block includes a hostaddress, the memory device can transition between modes using a detectedhost address change.

In an example, the amount of preloaded data can be received (e.g., froma manufacturer, user, etc.) or assumed, and a threshold amount can beset above that amount (e.g., 3 GB, 5 GB, 7 GB, etc.), or can otherwisebe configurable, manually or automatically, for example, based on thetype of memory device, the type of preloaded data, a descriptor in thepreloaded data, or an indication of the electronic device configured toinclude the memory device. Data can be stored in the memory device belowthe threshold amount in the reflow-protection mode (e.g., as SLC). Oncethe threshold amount has been exceeded, the memory device can transitionfrom the reflow-protection mode to the normal-operation mode, where datacan be stored in the memory device in a multi-level mode (e.g., as MLC).In an example, the memory device can transition upon receiving aninstruction that would write data to the memory array that would exceedthe threshold amount. In other examples, if an instruction to write datawould result in the stored data exceeding the threshold amount, thememory controller can provide a return error, then transition. In otherexamples, the memory controller can be configured to store the receiveddata in the reflow-protection mode, then test to see if the thresholdamount has been exceeded following execution of an instruction.

In other examples, the threshold amount can include received or assumednumber of logical block addressing (LBA) addresses. For example, datacan be stored on the memory device in the reflow-protection mode usingan initial number of LBA addresses. When the memory device receives aninstruction to write data to an LBA address different than (or differentfrom) the initial number (or initial set) of LBA, the memory device cantransition to the normal-operation mode. In other examples, one or moreother triggers or transitions can be used, such as a specific command,or an action outside of normal operation, such as holding reset for aperiod of time (e.g., 5 seconds, etc.).

In an example, instead of sending an instruction or flag to the memorydevice to transition from the single-level mode to the multi-level mode,the host device can write a dummy file to exceed the threshold amount ordummy file larger than the threshold amount (which can later be cleanedduring background operations in the normal-operation mode). In otherexamples, if the threshold amount is a number of power cycles, LBAaddress, or one or more other threshold amounts, the electronic devicecan, once assembly is complete, perform an operation to exceed thethreshold amount, or the electronic device can remain in thesingle-level mode after assembly until the threshold amount is exceeded,without significantly affecting the life or user-experience of theelectronic device.

In an example, if the memory device includes a number of memory dies(e.g., more than two), the memory controller can be configured to storethe preloaded data on a subset of the number of memory dies (e.g., 1 of8 memory dies, 2 of 8 memory dies, etc.) in the reflow-protection modeon the subset of memory dies as SLC. When the received data can nolonger be contained on the subset of memory dies, the memory controllercan transition to normal-operation, including storing received data onthe number of memory dies, or the remaining memory dies, as MLC.

In certain examples, data stored on the memory array in thereflow-protection mode (e.g., preloaded data, etc.) as SLC can berelocated to the memory array in the normal-operation mode as MLC. In anexample, once the memory device transitions from the reflow-protectionmode to the normal-operation mode, the memory cells used to store thedata in the reflow-protection mode can be reallocated from SLC to MLC(e.g., two-level cells, TLC, QLC, etc.), such as to fully utilize drivecapacity. In other examples, the memory array can be configured as othercombinations of SLC and MLC, depending on the electronic device, useconditions, etc.

In an example, the memory controller can be configured to suspend normalmedia management during the reflow-protection mode. For example,background operations, such as, for example, data migration, wearleveling, garbage collection, bad block management, or other errorcorrection or data management operations, may be suspended untilnormal-operation resumes. In an example, once the threshold amount ofdata has been received, and the memory controller transitions from thereflow-protection mode to the normal-operation mode, backgroundoperations can be re-enabled, and the memory controller can manage datapreviously stored on the drive, in case of errors or corruptions, as ifdata in the memory array has undergone one or more reflow processes(e.g., 3× reflow, etc.).

Electronic devices, such as mobile electronic devices (e.g., smartphones, tablets, etc.), electronic devices for use in automotiveapplications (e.g., automotive sensors, control units, driver-assistancesystems, passenger safety or comfort systems, etc.), andinternet-connected appliances or devices (e.g., internet-of-things (IoT)devices, etc.), have varying storage needs depending on, among otherthings, the type of electronic device, use environment, performanceexpectations, etc.

Electronic devices can be broken down into several main components: aprocessor (e.g., a central processing unit (CPU) or other mainprocessor); memory (e.g., one or more volatile or non-volatilerandom-access memory (RAM) memory device, such as dynamic RAM (DRAM),mobile or low-power double-data-rate synchronous DRAM (DDR SDRAM),etc.); and a storage device (e.g., non-volatile memory (NVM) device,such as flash memory, read-only memory (ROM), an SSD, an MMC, or othermemory card structure or assembly, etc.). In certain examples,electronic devices can include a user interface (e.g., a display,touch-screen, keyboard, one or more buttons, etc.), a graphicsprocessing unit (GPU), a power management circuit, a baseband processoror one or more transceiver circuits, etc.

FIG. 1 illustrates an example of an environment 100 including a hostdevice 105 and a memory device 110 configured to communicate over acommunication interface. The host device 105 or the memory device 110may be included in a variety of products 150, such as Internet of Things(IoT) devices (e.g., a refrigerator or other appliance, sensor, motor oractuator, mobile communication device, automobile, drone, etc.) tosupport processing, communications, or control of the product 150.

The memory device 110 includes a memory controller 115 and a memoryarray 120 including, for example, a number of individual memory die(e.g., a stack of three-dimensional (3D) NAND die). In 3D architecturesemiconductor memory technology, vertical structures are stacked,increasing the number of tiers, physical pages, and accordingly, thedensity of a memory device (e.g., a storage device). In an example, thememory device 110 can be a discrete memory or storage device componentof the host device 105. In other examples, the memory device 110 can bea portion of an integrated circuit (e.g., system on a chip (SOC), etc.),stacked or otherwise included with one or more other components of thehost device 105.

One or more communication interfaces can be used to transfer databetween the memory device 110 and one or more other components of thehost device 105, such as a Serial Advanced Technology Attachment (SATA)interface, a Peripheral Component Interconnect Express (PCIe) interface,a Universal Serial Bus (USB) interface, a Universal Flash Storage (UFS)interface, an eMMC™ interface, or one or more other connectors orinterfaces. The host device 105 can include a host system, an electronicdevice, a processor, a memory card reader, or one or more otherelectronic devices external to the memory device 110. In some examples,the host 105 may be a machine having some portion, or all, of thecomponents discussed in reference to the machine 500 of FIG. 5.

The memory controller 115 can receive instructions from the host 105,and can communicate with the memory array, such as to transfer data to(e.g., write or erase) or from (e.g., read) one or more of the memorycells, planes, sub-blocks, blocks, or pages of the memory array. Thememory controller 115 can include, among other things, circuitry orfirmware, including one or more components or integrated circuits. Forexample, the memory controller 115 can include one or more memorycontrol units, circuits, or components configured to control accessacross the memory array 120 and to provide a translation layer betweenthe host 105 and the memory device 110. The memory controller 115 caninclude one or more input/output (I/O) circuits, lines, or interfaces totransfer data to or from the memory array 120. The memory controller 115can include a memory manager 125 and an array controller 135.

The memory manager 125 can include, among other things, circuitry orfirmware, such as a number of components or integrated circuitsassociated with various memory management functions. For purposes of thepresent description example memory operation and management functionswill be described in the context of NAND memory. Persons skilled in theart will recognize that other forms of non-volatile memory may haveanalogous memory operations or management functions. Such NANDmanagement functions include wear leveling (e.g., garbage collection orreclamation), error detection or correction, block retirement, or one ormore other memory management functions. The memory manager 125 can parseor format host commands (e.g., commands received from a host) intodevice commands (e.g., commands associated with operation of a memoryarray, etc.), or generate device commands (e.g., to accomplish variousmemory management functions) for the array controller 135 or one or moreother components of the memory device 110.

The memory manager 125 can include a set of management tables 130configured to maintain various information associated with one or morecomponent of the memory device 110 (e.g., various information associatedwith a memory array or one or more memory cells coupled to the memorycontroller 115). For example, the management tables 130 can includeinformation regarding block age, block erase count, error history, orone or more error counts (e.g., a write operation error count, a readbit error count, a read operation error count, an erase error count,etc.) for one or more blocks of memory cells coupled to the memorycontroller 115. In certain examples, if the number of detected errorsfor one or more of the error counts is above a threshold, the bit errorcan be referred to as an uncorrectable bit error. The management tables130 can maintain a count of correctable or uncorrectable bit errors,among other things.

The array controller 135 can include, among other things, circuitry orcomponents configured to control memory operations associated withwriting data to, reading data from, or erasing one or more memory cellsof the memory device 110 coupled to the memory controller 115. Thememory operations can be based on, for example, host commands receivedfrom the host 105, or internally generated by the memory manager 125(e.g., in association with wear leveling, error detection or correction,etc.).

The array controller 135 can include an error correction code (ECC)component 140, which can include, among other things, an ECC engine orother circuitry configured to detect or correct errors associated withwriting data to or reading data from one or more memory cells of thememory device 110 coupled to the memory controller 115. The memorycontroller 115 can be configured to actively detect and recover fromerror occurrences (e.g., bit errors, operation errors, etc.) associatedwith various operations or storage of data, while maintaining integrityof the data transferred between the host 105 and the memory device 110,or maintaining integrity of stored data (e.g., using redundant RAIDstorage, etc.), and can remove (e.g., retire) failing memory resources(e.g., memory cells, memory arrays, pages, blocks, etc.) to preventfuture errors.

The memory array 120 can include several memory cells arranged in, forexample, a number of devices, planes, sub-blocks, blocks, or pages. Asone example, a 48 GB TLC NAND memory device can include 18,592 bytes (B)of data per page (16,384+2208 bytes), 1536 pages per block, 548 blocksper plane, and 4 or more planes per device. As another example, a 32 GBMLC memory device (storing two bits of data per cell (i.e., 4programmable states)) can include 18,592 bytes (B) of data per page(16,384+2208 bytes), 1024 pages per block, 548 blocks per plane, and 4planes per device, but with half the required write time and twice theprogram/erase (P/E) cycles as a corresponding TLC memory device. Otherexamples can include other numbers or arrangements. In some examples, amemory device, or a portion thereof, may be selectively operated in SLCmode, or in a desired MLC mode (such as TLC, QLC, etc.).

In operation, data is typically written to or read from the NAND memorydevice 110 in pages, and erased in blocks. However, one or more memoryoperations (e.g., read, write, erase, etc.) can be performed on largeror smaller groups of memory cells, as desired. The data transfer size ofa NAND memory device 110 is typically referred to as a page, whereas thedata transfer size of a host is typically referred to as a sector.

Although a page of data can include a number of bytes of user data(e.g., a data payload including a number of sectors of data) and itscorresponding metadata, the size of the page often refers only to thenumber of bytes used to store the user data. As an example, a page ofdata having a page size of 4 KB may include 4 KB of user data (e.g., 8sectors assuming a sector size of 512 B) as well as a number of bytes(e.g., 32 B, 54 B, 224 B, etc.) of metadata corresponding to the userdata, such as integrity data (e.g., error detecting or correcting codedata), address data (e.g., logical address data, etc.), or othermetadata associated with the user data.

Different types of memory cells or memory arrays 120 can provide fordifferent page sizes, or may require different amounts of metadataassociated therewith. For example, different memory device types mayhave different bit error rates, which can lead to different amounts ofmetadata necessary to ensure integrity of the page of data (e.g., amemory device with a higher bit error rate may require more bytes oferror correction code data than a memory device with a lower bit errorrate). As an example, a multi-level cell (MLC) NAND flash device mayhave a higher bit error rate than a corresponding single-level cell(SLC) NAND flash device. As such, the MLC device may require moremetadata bytes for error data than the corresponding SLC device.

FIG. 2 illustrates an example schematic diagram of a 3D NANDarchitecture semiconductor memory array 200 including a number ofstrings of memory cells (e.g., first-third A₀ memory strings205A₀-207A₀, first-third A_(n) memory strings 205A_(n)-207A_(n),first-third B₀ memory strings 205B₀-207B₀, first-third B_(n) memorystrings 205B_(n)-207B_(n), etc.), organized in blocks (e.g., block A201A, block B 201B, etc.) and sub-blocks (e.g., sub-block A₀ 201A₀,sub-block A_(n) 201A_(n), sub-block B₀ 201B₀, sub-block B_(n) 201B_(n),etc.). The memory array 200 represents a portion of a greater number ofsimilar structures that would typically be found in a block, device, orother unit of a memory device.

Each string of memory cells includes a number of tiers of charge storagetransistors (e.g., floating gate transistors, charge-trappingstructures, etc.) stacked in the Z direction, source to drain, between asource line (SRC) 235 or a source-side select gate (SGS) (e.g.,first-third A₀ SGS 231A₀-233A₀, first-third A_(n) SGS 231A_(n)-233A_(n),first-third B₀ SGS 231B₀-233B₀, first-third B_(n) SGS 231B_(n)-233 _(n),etc.) and a drain-side select gate (SGD) (e.g., first-third A₀ SGD226A₀-228A₀, first-third A_(n) SGD 226A_(n)-228A_(n), first-third B₀ SGD226B₀-228B₀, first-third B_(n) SGD 226B_(n)-228B_(n), etc.). Each stringof memory cells in the 3D memory array can be arranged along the Xdirection as data lines (e.g., bit lines (BL) BL0-BL2 220-222), andalong the Y direction as physical pages.

Within a physical page, each tier represents a row of memory cells, andeach string of memory cells represents a column. A sub-block can includeone or more physical pages. A block can include a number of sub-blocks(or physical pages) (e.g., 128, 256, 384, etc.). Although illustratedherein as having two blocks, each block having two sub-blocks, eachsub-block having a single physical page, each physical page having threestrings of memory cells, and each string having 8 tiers of memory cells,in other examples, the memory array 200 can include more or fewerblocks, sub-blocks, physical pages, strings of memory cells, memorycells, or tiers. For example, each string of memory cells can includemore or fewer tiers (e.g., 16, 32, 64, 128, etc.), as well as one ormore additional tiers of semiconductor material above or below thecharge storage transistors (e.g., select gates, data lines, etc.), asdesired. As an example, a 48 GB TLC NAND memory device can include18,592 bytes (B) of data per page (16,384+2208 bytes), 1536 pages perblock, 548 blocks per plane, and 4 or more planes per device.

Each memory cell in the memory array 200 includes a control gate (CG)coupled to (e.g., electrically or otherwise operatively connected to) anaccess line (e.g., word lines (WL) WL0 ₀-WL7 ₀ 210A-217A, WL0 ₁-WL7 ₁210B-217B, etc.), which collectively couples the control gates (CGs)across a specific tier, or a portion of a tier, as desired. Specifictiers in the 3D memory array, and accordingly, specific memory cells ina string, can be accessed or controlled using respective access lines.Groups of select gates can be accessed using various select lines. Forexample, first-third A₀ SGD 226A₀-228A₀ can be accessed using an A₀ SGDline SGDA₀ 225A₀, first-third A_(n) SGD 226A_(n)-228A_(n) can beaccessed using an A_(n) SGD line SGDA_(n) 225A_(n), first-third B₀ SGD226B₀-228B₀ can be accessed using an B₀ SGD line SGDB₀ 225B₀, andfirst-third B_(n) SGD 226B_(n)-228B_(n) can be accessed using an B_(n)SGD line SGDB_(n) 225B_(n). First-third A₀ SGS 231A₀-233A₀ andfirst-third A_(n) SGS 231A_(n)-233A_(n) can be accessed using a gateselect line SGS₀ 230A, and first-third B₀ SGS 231B₀-233B₀ andfirst-third B_(n) SGS 231B_(n)-233B_(n) can be accessed using a gateselect line SGS₁ 230B.

In an example, the memory array 200 can include a number of levels ofsemiconductor material (e.g., polysilicon, etc.) configured to couplethe control gates (CGs) of each memory cell or select gate (or a portionof the CGs or select gates) of a respective tier of the array. Specificstrings of memory cells in the array can be accessed, selected, orcontrolled using a combination of bit lines (BLs) and select gates,etc., and specific memory cells at one or more tiers in the specificstrings can be accessed, selected, or controlled using one or moreaccess lines (e.g., word lines).

FIG. 3 illustrates an example schematic diagram of a portion of a NANDarchitecture semiconductor memory array 300 including a plurality ofmemory cells 302 arranged in a two-dimensional array of strings (e.g.,first-third strings 305-307) and tiers (e.g., illustrated as respectiveword lines (WL) WL0-WL7 310-317, a drain-side select gate (SGD) line325, a source-side select gate (SGS) line 330, etc.), and senseamplifiers or devices 360. For example, the memory array 300 canillustrate an example schematic diagram of a portion of one physicalpage of memory cells of a 3D NAND architecture semiconductor memorydevice, such as illustrated in FIG. 2.

Each string of memory cells is coupled to a source line (SRC) using arespective source-side select gate (SGS) (e.g., first-third SGS331-333), and to a respective data line (e.g., first-third bit lines(BL) BL0-BL2 320-322) using a respective drain-side select gate (SGD)(e.g., first-third SGD 326-328). Although illustrated with 8 tiers(e.g., using word lines (WL) WL0-WL7 310-317) and three data lines(BL0-BL2 326-328) in the example of FIG. 3, other examples can includestrings of memory cells having more or fewer tiers or data lines, asdesired.

In a NAND architecture semiconductor memory array, such as the examplememory array 300, the state of a selected memory cell 302 can beaccessed by sensing a current or voltage variation associated with aparticular data line containing the selected memory cell. The memoryarray 300 can be accessed (e.g., by a control circuit, one or moreprocessors, digital logic, etc.) using one or more drivers. In anexample, one or more drivers can activate a specific memory cell, or setof memory cells, by driving a particular potential to one or more datalines (e.g., bit lines BL0-BL2), access lines (e.g., word linesWL0-WL7), or select gates, depending on the type of operation desired tobe performed on the specific memory cell or set of memory cells.

To program or write data to a memory cell, a programming voltage (Vpgm)(e.g., one or more programming pulses, etc.) can be applied to selectedword lines (e.g., WL4), and thus, to a control gate of each memory cellcoupled to the selected word lines (e.g., first-third control gates(CGs) 341-343 of the memory cells coupled to WL4). Programming pulsescan begin, for example, at or near 15V, and, in certain examples, canincrease in magnitude during each programming pulse application. Whilethe program voltage is applied to the selected word lines, a potential,such as a ground potential (e.g., Vss), can be applied to the data lines(e.g., bit lines) and substrates (and thus the channels, between thesources and drains) of the memory cells targeted for programming,resulting in a charge transfer (e.g., direct injection orFowler-Nordheim (FN) tunneling, etc.) from the channels to the floatinggates of the targeted memory cells.

In contrast, a pass voltage (Vpass) can be applied to one or more wordlines having memory cells that are not targeted for programming, or aninhibit voltage (e.g., Vcc) can be applied to data lines (e.g., bitlines) having memory cells that are not targeted for programming, forexample, to inhibit charge from being transferred from the channels tothe floating gates of such non-targeted memory cells. The pass voltagecan be variable, depending, for example, on the proximity of the appliedpass voltages to a word line targeted for programming. The inhibitvoltage can include a supply voltage (Vcc), such as a voltage from anexternal source or supply (e.g., a battery, an AC-to-DC converter,etc.), relative to a ground potential (e.g., Vss).

As an example, if a programming voltage (e.g., 15V or more) is appliedto a specific word line, such as WL4, a pass voltage of 10V can beapplied to one or more other word lines, such as WL3, WL5, etc., toinhibit programming of non-targeted memory cells, or to retain thevalues stored on such memory cells not targeted for programming. As thedistance between an applied program voltage and the non-targeted memorycells increases, the pass voltage required to refrain from programmingthe non-targeted memory cells can decrease. For example, where aprogramming voltage of 15V is applied to WL4, a pass voltage of 10V canbe applied to WL3 and WL5, a pass voltage of 8V can be applied to WL2and WL6, a pass voltage of 7V can be applied to WL1 and WL7, etc. Inother examples, the pass voltages, or number of word lines, etc., can behigher or lower, or more or less.

The sense amplifiers 360, coupled to one or more of the data lines(e.g., first, second, or third bit lines (BL0-BL2) 320-322), can detectthe state of each memory cell in respective data lines by sensing avoltage or current on a particular data line.

Between applications of one or more programming pulses (e.g., Vpgm), averify operation can be performed to determine if a selected memory cellhas reached its intended programmed state. If the selected memory cellhas reached its intended programmed state, it can be inhibited fromfurther programming. If the selected memory cell has not reached itsintended programmed state, additional programming pulses can be applied.If the selected memory cell has not reached its intended programmedstate after a particular number of programming pulses (e.g., a maximumnumber), the selected memory cell, or a string, block, or pageassociated with such selected memory cell, can be marked as defective.

To erase a memory cell or a group of memory cells (e.g., erasure istypically performed in blocks or sub-blocks), an erasure voltage (Vers)(e.g., typically Vpgm) can be applied to the substrates (and thus thechannels, between the sources and drains) of the memory cells targetedfor erasure (e.g., using one or more bit lines, select gates, etc.),while the word lines of the targeted memory cells are kept at apotential, such as a ground potential (e.g., Vss), resulting in a chargetransfer (e.g., direct injection or Fowler-Nordheim (FN) tunneling,etc.) from the floating gates of the targeted memory cells to thechannels.

FIG. 4 illustrates an example block diagram of a memory device 400including a memory array 402 having a plurality of memory cells 404, andone or more circuits or components to provide communication with, orperform one or more memory operations on, the memory array 402. Thememory device 400 can include a row decoder 412, a column decoder 414,sense amplifiers 420, a page buffer 422, a selector 424, an input/output(I/O) circuit 426, and a memory control unit 430.

The memory cells 404 of the memory array 402 can be arranged in blocks,such as first and second blocks 402A, 402B. Each block can includesub-blocks. For example, the first block 402A can include first andsecond sub-blocks 402A₀, 402A_(n), and the second block 402B can includefirst and second sub-blocks 402B₀, 402B_(n). Each sub-block can includea number of physical pages, each page including a number of memory cells404. Although illustrated herein as having two blocks, each block havingtwo sub-blocks, and each sub-block having a number of memory cells 404,in other examples, the memory array 402 can include more or fewerblocks, sub-blocks, memory cells, etc. In other examples, the memorycells 404 can be arranged in a number of rows, columns, pages,sub-blocks, blocks, etc., and accessed using, for example, access lines406, first data lines 410, or one or more select gates, source lines,etc.

The memory control unit 430 can control memory operations of the memorydevice 400 according to one or more signals or instructions received oncontrol lines 432, including, for example, one or more clock signals orcontrol signals that indicate a desired operation (e.g., write, read,erase, etc.), or address signals (A0-AX) received on one or more addresslines 416. One or more devices external to the memory device 400 cancontrol the values of the control signals on the control lines 432, orthe address signals on the address line 416. Examples of devicesexternal to the memory device 400 can include, but are not limited to, ahost, a memory controller, a processor, or one or more circuits orcomponents not illustrated in FIG. 4.

The memory device 400 can use access lines 406 and first data lines 410to transfer data to (e.g., write or erase) or from (e.g., read) one ormore of the memory cells 404. The row decoder 412 and the column decoder414 can receive and decode the address signals (A0-AX) from the addressline 416, can determine which of the memory cells 404 are to beaccessed, and can provide signals to one or more of the access lines 406(e.g., one or more of a plurality of word lines (WL0-WLm)) or the firstdata lines 410 (e.g., one or more of a plurality of bit lines(BL0-BLn)), such as described above.

The memory device 400 can include sense circuitry, such as the senseamplifiers 420, configured to determine the values of data on (e.g.,read), or to determine the values of data to be written to, the memorycells 404 using the first data lines 410. For example, in a selectedstring of memory cells 404, one or more of the sense amplifiers 420 canread a logic level in the selected memory cell 404 in response to a readcurrent flowing in the memory array 402 through the selected string tothe data lines 410.

One or more devices external to the memory device 400 can communicatewith the memory device 400 using the I/O lines (DQ0-DQN) 408, addresslines 416 (A0-AX), or control lines 432. The input/output (I/O) circuit426 can transfer values of data in or out of the memory device 400, suchas in or out of the page buffer 422 or the memory array 402, using theI/O lines 408, according to, for example, the control lines 432 andaddress lines 416. The page buffer 422 can store data received from theone or more devices external to the memory device 400 before the data isprogrammed into relevant portions of the memory array 402, or can storedata read from the memory array 402 before the data is transmitted tothe one or more devices external to the memory device 400.

The column decoder 414 can receive and decode address signals (A0-AX)into one or more column select signals (CSEL1-CSELn). The selector 424(e.g., a select circuit) can receive the column select signals(CSEL1-CSELn) and select data in the page buffer 422 representing valuesof data to be read from or to be programmed into memory cells 404.Selected data can be transferred between the page buffer 422 and the I/Ocircuit 426 using second data lines 418.

The memory control unit 430 can receive positive and negative supplysignals, such as a supply voltage (Vcc) 434 and a negative supply (Vss)436 (e.g., a ground potential), from an external source or supply (e.g.,an internal or external battery, an AC-to-DC converter, etc.). Incertain examples, the memory control unit 430 can include a regulator428 to internally provide positive or negative supply signals.

FIGS. 5A-5B illustrate example charge distributions, including anexample single-level cells (SLC) charge distribution 500 and an examplemulti-level cells (MLC) charge distribution 501. In FIG. 5A, the SLCcharge distribution 500 illustrates two available states (“1” and “0”)separated by a reference point. The value of the reference point andscale of the threshold voltage (Vt) of a cell depends on, among otherthings, the logic level of the memory device. In FIG. 5B, the MLC chargedistribution 501 (in this example, two-level cells) illustrates fourpossible states (“11”, “10”, “01”, and “00”) separated by multiplereference points. The margin between the voltage distributions andreference points are narrower in MLC than SLC, and more susceptible tocorruption from cell leakage and voltage shift when exposed to hightemperatures (e.g., greater than 180° C., greater than 200° C., greaterthan 220° C., etc.).

FIG. 6 illustrates an example block diagram of an electronic device 600including a memory device 610, the memory device 610 including a memorycontroller 615 and a memory array 620. The memory array 620 can beoperated in a number of modes, including, for example, areflow-protection mode (e.g., a single-level mode), and anormal-operation mode (e.g., a multi-level mode). In thereflow-protection mode, the memory array 620 can include a number ofblocks, including an SLC block 602. In an example, when a threshold isreached, such as a threshold amount of data stored on or written to thememory array 620, a number of power cycles for the memory device 610, anumber of LBA addresses used or written by the memory device 610, or oneor more other thresholds or threshold conditions, the memory device 610can transition the memory array 620 from the reflow-protection mode(e.g., as single-level memory cells (SLC)) to the normal-operation mode(e.g., as multi-level cells, such as two-level cells, three-level cells(TLC), four-level cells (QLC), etc.). In an example, the SLC block 602can be transitioned to an MLC block, such as a TLC block, etc.

FIG. 7 illustrates an example method 700 for managing a memory device.At 701, data, including preloaded data, can be stored on or written to amemory array in a reflow-protection mode as SLC. At 702, the amount ofdata written to, being written to, stored on the memory array, orinstructed to be stored on the memory array in the reflow-protectionmode can be compared to a threshold amount. In an example, the memorycontroller can receive information from a host device, and can establishthe threshold amount using the received information, e.g., prior toreceiving preloaded data. In other examples, the threshold amount can beset in the memory controller without reference to the host device. In anexample, comparison of the threshold amount can decide operation flowwithout receiving a separate verification of preloaded data, such asfrom the host device or a device providing the preloaded data to thememory device, or without receiving a separate indication of completedreflow or assembly. In an example, comparison of the data, includingpreloaded data, stored on the memory device to the threshold amount,alone, can control.

If, at 702, the data written to, being written to, stored on the memoryarray, or instructed to be stored on the memory array in thereflow-protection mode does not or has not exceeded a threshold amount,data can continue to be stored on or written to the memory array as SLCat 701. If, at 702, the data written to, being written to, stored on thememory array, or instructed to be stored on the memory array in thereflow-protection mode exceeds the threshold amount, the memory arraycan transition from the reflow-protection mode to a normal-operationmode at 703, and can optionally relocate, rewrite, or re-store the datastored in the reflow-protection mode to the same or another location onthe memory array as MLC (e.g., two-level cells, TLC, QLC, etc.), or in anormal-operation (e.g., a multi-level or second mode), optionally aftera power-on (e.g., restart, power-on reset, etc.) after the thresholdamount is exceeded. Subsequent data, at or above the threshold amount,can be stored on or written to the memory array as MLC, such as afterdata written to, being written to, stored on the memory array, orinstructed to be stored on the memory array exceeds the threshold amountat 702, and optionally, after a power-on after the threshold amount isexceeded.

In other examples, instead of the reflow-protection mode and thenormal-operation mode (e.g., two-level mode, three-level mode, fourlevel mode, etc.), the modes can include a first, lower-level mode and asecond, higher-level mode. In an example, the first mode can include atwo-level mode (e.g., two-level cells) and the second mode can include athree-level mode (e.g., TLC), a four-level mode (e.g., QLC), etc. In anexample, the first mode can include a three-level mode and the secondmode can include a four-level mode (or higher).

FIG. 8 illustrates a block diagram of an example machine 800 upon whichany one or more of the techniques (e.g., methodologies) discussed hereinmay perform. In alternative embodiments, the machine 800 may operate asa standalone device or may be connected (e.g., networked) to othermachines. In a networked deployment, the machine 800 may operate in thecapacity of a server machine, a client machine, or both in server-clientnetwork environments. In an example, the machine 800 may act as a peermachine in peer-to-peer (P2P) (or other distributed) networkenvironment. The machine 800 may be a personal computer (PC), a tabletPC, a set-top box (STB), a personal digital assistant (PDA), a mobiletelephone, a web appliance, an IoT device, automotive system, or anymachine capable of executing instructions (sequential or otherwise) thatspecify actions to be taken by that machine. Further, while only asingle machine is illustrated, the term “machine” shall also be taken toinclude any collection of machines that individually or jointly executea set (or multiple sets) of instructions to perform any one or more ofthe methodologies discussed herein, such as cloud computing, software asa service (SaaS), other computer cluster configurations.

Examples, as described herein, may include, or may operate by, logic,components, devices, packages, or mechanisms. Circuitry is a collection(e.g., set) of circuits implemented in tangible entities that includehardware (e.g., simple circuits, gates, logic, etc.). Circuitrymembership may be flexible over time and underlying hardwarevariability. Circuitries include members that may, alone or incombination, perform specific tasks when operating. In an example,hardware of the circuitry may be immutably designed to carry out aspecific operation (e.g., hardwired). In an example, the hardware of thecircuitry may include variably connected physical components (e.g.,execution units, transistors, simple circuits, etc.) including acomputer readable medium physically modified (e.g., magnetically,electrically, moveable placement of invariant massed particles, etc.) toencode instructions of the specific operation. In connecting thephysical components, the underlying electrical properties of a hardwareconstituent are changed, for example, from an insulator to a conductoror vice versa. The instructions enable participating hardware (e.g., theexecution units or a loading mechanism) to create members of thecircuitry in hardware via the variable connections to carry out portionsof the specific tasks when in operation. Accordingly, the computerreadable medium is communicatively coupled to the other components ofthe circuitry when the device is operating. In an example, any of thephysical components may be used in more than one member of more than onecircuitry. For example, under operation, execution units may be used ina first circuit of a first circuitry at one point in time and reused bya second circuit in the first circuitry, or by a third circuit in asecond circuitry at a different time.

The machine (e.g., computer system) 800 (e.g., the host device 105, thememory device 110, etc.) may include a hardware processor 802 (e.g., acentral processing unit (CPU), a graphics processing unit (GPU), ahardware processor core, or any combination thereof, such as the memorycontroller 115, etc.), a main memory 804 and a static memory 806, someor all of which may communicate with each other via an interlink (e.g.,bus) 808. The machine 800 may further include a display unit 810, analphanumeric input device 812 (e.g., a keyboard), and a user interface(UI) navigation device 814 (e.g., a mouse). In an example, the displayunit 810, input device 812 and UI navigation device 814 may be a touchscreen display. The machine 800 may additionally include a storagedevice (e.g., drive unit) 816, a signal generation device 818 (e.g., aspeaker), a network interface device 820, and one or more sensors 816,such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The machine 800 may include an outputcontroller 828, such as a serial (e.g., universal serial bus (USB),parallel, or other wired or wireless (e.g., infrared (IR), near fieldcommunication (NFC), etc.) connection to communicate or control one ormore peripheral devices (e.g., a printer, card reader, etc.).

The storage device 816 may include a machine readable medium 822 onwhich is stored one or more sets of data structures or instructions 824(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 824 may alsoreside, completely or at least partially, within the main memory 804,within static memory 806, or within the hardware processor 802 duringexecution thereof by the machine 800. In an example, one or anycombination of the hardware processor 802, the main memory 804, thestatic memory 806, or the storage device 816 may constitute the machinereadable medium 822.

While the machine readable medium 822 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, orassociated caches and servers) configured to store the one or moreinstructions 824.

The term “machine readable medium” may include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 800 and that cause the machine 800 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding or carrying data structures used by or associated withsuch instructions. Non-limiting machine readable medium examples mayinclude solid-state memories, and optical and magnetic media. In anexample, a massed machine readable medium comprises a machine-readablemedium with a plurality of particles having invariant (e.g., rest) mass.Accordingly, massed machine-readable media are not transitorypropagating signals. Specific examples of massed machine readable mediamay include: non-volatile memory, such as semiconductor memory devices(e.g., Electrically Programmable Read-Only Memory (EPROM), ElectricallyErasable Programmable Read-Only Memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

The instructions 824 (e.g., software, programs, an operating system(OS), etc.) or other data are stored on the storage device 821, can beaccessed by the memory 804 for use by the processor 802. The memory 804(e.g., DRAM) is typically fast, but volatile, and thus a different typeof storage than the storage device 821 (e.g., an SSD), which is suitablefor long-term storage, including while in an “off” condition. Theinstructions 824 or data in use by a user or the machine 800 aretypically loaded in the memory 804 for use by the processor 802. Whenthe memory 804 is full, virtual space from the storage device 821 can beallocated to supplement the memory 804; however, because the storage 821device is typically slower than the memory 804, and write speeds aretypically at least twice as slow as read speeds, use of virtual memorycan greatly reduce user experience due to storage device latency (incontrast to the memory 804, e.g., DRAM). Further, use of the storagedevice 821 for virtual memory can greatly reduce the usable lifespan ofthe storage device 821.

In contrast to virtual memory, virtual memory compression (e.g., theLinux® kernel feature “ZRAM”) uses part of the memory as compressedblock storage to avoid paging to the storage device 821. Paging takesplace in the compressed block until it is necessary to write such datato the storage device 821. Virtual memory compression increases theusable size of memory 804, while reducing wear on the storage device821.

Storage devices optimized for mobile electronic devices, or mobilestorage, traditionally include MMC solid-state storage devices (e.g.,micro Secure Digital (microSD™) cards, etc.). MMC devices include anumber of parallel interfaces (e.g., an 8-bit parallel interface) with ahost device, and are often removable and separate components from thehost device. In contrast, eMMC™ devices are attached to a circuit boardand considered a component of the host device, with read speeds thatrival serial ATA™ (Serial AT (Advanced Technology) Attachment, or SATA)based SSD devices. However, demand for mobile device performancecontinues to increase, such as to fully enable virtual oraugmented-reality devices, utilize increasing networks speeds, etc. Inresponse to this demand, storage devices have shifted from parallel toserial communication interfaces. Universal Flash Storage (UFS) devices,including controllers and firmware, communicate with a host device usinga low-voltage differential signaling (LVDS) serial interface withdedicated read/write paths, further advancing greater read/write speeds.

The instructions 824 may further be transmitted or received over acommunications network 826 using a transmission medium via the networkinterface device 820 utilizing any one of a number of transfer protocols(e.g., frame relay, Internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards,peer-to-peer (P2P) networks, among others. In an example, the networkinterface device 820 may include one or more physical jacks (e.g.,Ethernet, coaxial, or phone jacks) or one or more antennas to connect tothe communications network 826. In an example, the network interfacedevice 820 may include a plurality of antennas to wirelessly communicateusing at least one of single-input multiple-output (SIMO),multiple-input multiple-output (MIMO), or multiple-input single-output(MISO) techniques. The term “transmission medium” shall be taken toinclude any intangible medium that is capable of storing, encoding orcarrying instructions for execution by the machine 800, and includesdigital or analog communications signals or other intangible medium tofacilitate communication of such software.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples”. Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples one or more aspects thereof) shown or described herein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” may include “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein”. Also, in the following claims, theterms “including” and “comprising” are open-ended, that is, a system,device, article, or process that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim. Moreover, in the following claims, the terms“first,” “second,” and “third,” etc. are used merely as labels, and arenot intended to impose numerical requirements on their objects.

In various examples, the components, controllers, processors, units,engines, or tables described herein can include, among other things,physical circuitry or firmware stored on a physical device. As usedherein, “processor” means any type of computational circuit such as, butnot limited to, a microprocessor, a microcontroller, a graphicsprocessor, a digital signal processor (DSP), or any other type ofprocessor or processing circuit, including a group of processors ormulti-core devices.

The term “horizontal” as used in this document is defined as a planeparallel to the conventional plane or surface of a substrate, such asthat underlying a wafer or die, regardless of the actual orientation ofthe substrate at any point in time. The term “vertical” refers to adirection perpendicular to the horizontal as defined above.Prepositions, such as “on,” “over,” and “under” are defined with respectto the conventional plane or surface being on the top or exposed surfaceof the substrate, regardless of the orientation of the substrate; andwhile “on” is intended to suggest a direct contact of one structurerelative to another structure which it lies “on” (in the absence of anexpress indication to the contrary); the terms “over” and “under” areexpressly intended to identify a relative placement of structures (orlayers, features, etc.), which expressly includes—but is not limitedto—direct contact between the identified structures unless specificallyidentified as such. Similarly, the terms “over” and “under” are notlimited to horizontal orientations, as a structure may be “over” areferenced structure if it is, at some point in time, an outermostportion of the construction under discussion, even if such structureextends vertically relative to the referenced structure, rather than ina horizontal orientation.

The terms “wafer” and “substrate” are used herein to refer generally toany structure on which integrated circuits are formed, and also to suchstructures during various stages of integrated circuit fabrication. Thefollowing detailed description is, therefore, not to be taken in alimiting sense, and the scope of the various embodiments is defined onlyby the appended claims, along with the full scope of equivalents towhich such claims are entitled.

Various embodiments according to the present disclosure and describedherein include memory utilizing a vertical structure of memory cells(e.g., NAND strings of memory cells). As used herein, directionaladjectives will be taken relative a surface of a substrate upon whichthe memory cells are formed (i.e., a vertical structure will be taken asextending away from the substrate surface, a bottom end of the verticalstructure will be taken as the end nearest the substrate surface and atop end of the vertical structure will be taken as the end farthest fromthe substrate surface).

As used herein, directional adjectives, such as horizontal, vertical,normal, parallel, perpendicular, etc., can refer to relativeorientations, and are not intended to require strict adherence tospecific geometric properties, unless otherwise noted. For example, asused herein, a vertical structure need not be strictly perpendicular toa surface of a substrate, but may instead be generally perpendicular tothe surface of the substrate, and may form an acute angle with thesurface of the substrate (e.g., between 60 and 120 degrees, etc.).

In some embodiments described herein, different doping configurationsmay be applied to a source-side select gate (SGS), a control gate (CG),and a drain-side select gate (SGD), each of which, in this example, maybe formed of or at least include polysilicon, with the result such thatthese tiers (e.g., polysilicon, etc.) may have different etch rates whenexposed to an etching solution. For example, in a process of forming amonolithic pillar in a 3D semiconductor device, the SGS and the CG mayform recesses, while the SGD may remain less recessed or even notrecessed. These doping configurations may thus enable selective etchinginto the distinct tiers (e.g., SGS, CG, and SGD) in the 3D semiconductordevice by using an etching solution (e.g., tetramethylammonium hydroxide(TMCH)).

Operating a memory cell, as used herein, includes reading from, writingto, or erasing the memory cell. The operation of placing a memory cellin an intended state is referred to herein as “programming,” and caninclude both writing to or erasing from the memory cell (e.g., thememory cell may be programmed to an erased state).

According to one or more embodiments of the present disclosure, a memorycontroller (e.g., a processor, controller, firmware, etc.) locatedinternal or external to a memory device, is capable of determining(e.g., selecting, setting, adjusting, computing, changing, clearing,communicating, adapting, deriving, defining, utilizing, modifying,applying, etc.) a quantity of wear cycles, or a wear state (e.g.,recording wear cycles, counting operations of the memory device as theyoccur, tracking the operations of the memory device it initiates,evaluating the memory device characteristics corresponding to a wearstate, etc.)

According to one or more embodiments of the present disclosure, a memoryaccess device may be configured to provide wear cycle information to thememory device with each memory operation. The memory device controlcircuitry (e.g., control logic) may be programmed to compensate formemory device performance changes corresponding to the wear cycleinformation. The memory device may receive the wear cycle informationand determine one or more operating parameters (e.g., a value,characteristic) in response to the wear cycle information.

It will be understood that when an element is referred to as being “on,”“connected to” or “coupled with” another element, it can be directly on,connected, or coupled with the other element or intervening elements maybe present. In contrast, when an element is referred to as being“directly on,” “directly connected to” or “directly coupled with”another element, there are no intervening elements or layers present. Iftwo elements are shown in the drawings with a line connecting them, thetwo elements can be either be coupled, or directly coupled, unlessotherwise indicated.

Method examples described herein can be machine or computer-implementedat least in part. Some examples can include a computer-readable mediumor machine-readable medium encoded with instructions operable toconfigure an electronic device to perform methods as described in theabove examples. An implementation of such methods can include code, suchas microcode, assembly language code, a higher-level language code, orthe like. Such code can include computer readable instructions forperforming various methods. The code may form portions of computerprogram products. Further, the code can be tangibly stored on one ormore volatile or non-volatile tangible computer-readable media, such asduring execution or at other times. Examples of these tangiblecomputer-readable media can include, but are not limited to, hard disks,removable magnetic disks, removable optical disks (e.g., compact discsand digital video disks), magnetic cassettes, memory cards or sticks,random access memories (RAMS), read only memories (ROMs), solid statedrives (SSDs), Universal Flash Storage (UFS) device, embedded MMC (eMMC)device, and the like.

Example 1 is a memory device configured to reduce corruption ofpreloaded data during assembly, the memory device comprising: a memoryarray having groups of multiple blocks of memory cells; and a memorycontroller operably coupled to the memory array, the memory controllerto perform operations comprising: store received data, includingpreloaded data, up to a threshold amount on the memory array in areflow-protection mode; and transition from the reflow-protection modeto a normal-operation mode after the received data exceeds the thresholdamount.

In Example 2, the subject matter of Example 1 optionally includeswherein the memory controller is configured to write the received datain the reflow-protection mode on the memory array as single-level cells(SLC), and to write received data in the normal-operation mode asmulti-level cells (MLC).

In Example 3, the subject matter of Example 2 optionally includeswherein, after the received data exceeds the threshold amount, thememory controller is configured to write the received data stored in thereflow-protection mode as SLC to the memory array as MLC.

In Example 4, the subject matter of any one or more of Examples 1-3optionally include wherein the memory controller is configured toperform background operations in the normal-operation mode, and tosuspend background operations in the reflow-protection mode, whereinbackground operations include data migration.

In Example 5, the subject matter of any one or more of Examples 1-4optionally include wherein the reflow-protection mode has a greaterthreshold temperature margin than the normal-operation mode, wherein thethreshold amount is greater than the amount of preloaded data includinga kernel and pre-loaded software for an electronic device configured toinclude the memory device, and wherein the memory controller isconfigured to store the preloaded data on the memory array in thereflow-protection mode as SLC to reduce corruption of the preloaded dataduring assembly of the electronic device including the memory device.

In Example 6, the subject matter of Example 5 optionally includeswherein, because the threshold amount is greater than the amount ofpreloaded data, the memory device is configured to store received datain the reflow-protection mode for a short time after assembly of theelectronic device, then transition after assembly of the electronicdevice to the normal-operation mode after the received data exceeds thethreshold amount, without receiving a separate indication from a hostdevice of completed assembly.

In Example 7, the subject matter of any one or more of Examples 5-6optionally include D) NAND memory array.

In Example 8, the subject matter of any one or more of Examples 1-7optionally include wherein the memory controller is configured toreceive the threshold amount from a host device prior to receiving thepreloaded data.

In Example 9, the subject matter of any one or more of Examples 1-8optionally include gigabytes (GB) of data.

In Example 10, the subject matter of any one or more of Examples 1-9optionally include wherein the memory controller is configured totransition from the reflow-protection mode to the normal-operation modewithout receiving a separate verification of preloaded data.

In Example 11, the subject matter of any one or more of Examples 1-10optionally include wherein the memory controller is configured totransition from the reflow-protection mode to the normal-operation modewithout receiving a separate indication of completed assembly.

Example 12 is a method for managing a memory device to reduce corruptionof preloaded data during assembly, the method comprising a number ofoperations performed by a memory controller of a memory array, thememory array having groups of multiple blocks of memory cells, theoperations comprising: storing received data, including preloaded data,up to a threshold amount on a memory array memory array in areflow-protection mode; transitioning from the reflow-protection mode toa normal-operation mode after the received data exceeds the thresholdamount.

In Example 13, the subject matter of Example 12 optionally includes theoperations comprising: writing received data in the reflow-protectionmode on the memory array as single-level cells (SLC); and writingreceived data in the normal-operation mode on the memory array asmulti-level cells (MLC), wherein preloaded data includes a kernel andpre-loaded software for an electronic device configured to include thememory device, and wherein writing received data in thereflow-protection mode as SLC includes to reduce corruption of thepreloaded data during assembly of the electronic device including thememory device.

In Example 14, the subject matter of Example 13 optionally includeswherein transitioning from the reflow-protection mode to thenormal-operation mode includes writing the received data stored in thereflow-protection mode as SLC to the memory array as MLC.

In Example 15, the subject matter of any one or more of Examples 12-14optionally include the operations comprising: performing backgroundoperations on the memory device in the normal-operation mode; andsuspending background operations in the reflow-protection mode, whereinbackground operations include data migration.

In Example 16, the subject matter of any one or more of Examples 12-15optionally include the operations comprising: receiving the thresholdamount from a host device prior to receiving the preloaded data.

In Example 17, the subject matter of any one or more of Examples 12-16optionally include wherein transitioning from the reflow-protection modeto the normal-operation mode includes without receiving a separateverification of preloaded data, or without receiving a separateindication of completed assembly.

Example 18 is a device readable storage medium, that providesinstructions that, when executed by a memory controller of a memorydevice, cause the memory controller to perform operations to reducecorruption of preloaded data during assembly, the operations comprising:store received data, including preloaded data, up to a threshold amounton a memory array memory array in a reflow-protection mode; transitionfrom the reflow-protection mode to a normal-operation mode after thereceived data exceeds the threshold amount.

In Example 19, the subject matter of Example 18 optionally includes theoperations comprising: write received data in the reflow-protection modeon the memory array as single-level cells (SLC) to reduce corruption ofthe preloaded data during assembly of an electronic device including thememory device, wherein the preloaded data includes a kernel andpre-loaded software for the electronic device; and write received datain the normal-operation mode on the memory array as multi-level cells(MLC).

In Example 20, the subject matter of any one or more of Examples 18-19optionally include wherein the operation to transition from thereflow-protection mode to the normal-operation mode includes to writethe received data stored in the reflow-protection mode as SLC to thememory array as MLC.

In Example 21, the subject matter of any one or more of Examples 18-20optionally include the operations comprising: perform backgroundoperations on the memory device in the normal-operation mode; andsuspend background operations in the reflow-protection mode, whereinbackground operations include data migration.

In Example 22, the subject matter of any one or more of Examples 18-21optionally include the operations comprising: receive the thresholdamount from a host device prior to receiving the preloaded data.

In Example 23, the subject matter of any one or more of Examples 18-22optionally include wherein the operation to transition from thereflow-protection mode to the normal-operation mode includes withoutreceiving a separate verification of preloaded data, or withoutreceiving a separate indication of completed assembly.

Example 24 is a device readable storage medium, that providesinstructions that, when executed by a controller of a memory device,optimizes voltage read level calibration in the memory device, whereinthe instructions cause the controller to perform operations according toany of the techniques of Examples 1-23.

Example 25 is an apparatus comprising respective means for performingany of the methods or techniques of Examples 1-23.

Example 26 is a system, apparatus, or device to perform the operationsof any of Examples 1-23.

Example 27 is a tangible machine readable medium embodying instructionsto perform or implement the operations of any of Examples 1-23.

Example 28 is a method to perform the operations of any of Examples1-23.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment, and it is contemplated that such embodiments can be combinedwith each other in various combinations or permutations. The scope ofthe invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

The invention claimed is:
 1. A memory device configured to reducecorruption of received data during assembly, the memory devicecomprising: a memory array having groups of multiple blocks of memorycells; and a memory controller operably coupled to the memory array, thememory controller to perform operations comprising: store received dataon the memory array in a first mode having a first threshold temperaturemargin until the received data exceeds a threshold amount; andtransition from the first mode to a second mode having a secondthreshold temperature margin after the received data exceeds thethreshold amount, wherein the second threshold temperature margin isless than the first threshold temperature margin.
 2. The memory deviceof claim 1, wherein the memory controller is configured to storereceived data, including preloaded data, on the memory array in thefirst mode until the received data exceeds the threshold amount, whereinthe threshold amount is greater than the preloaded data, wherein thefirst mode is a reflow-protection mode and the second mode is anormal-operation mode.
 3. The memory device of claim 2, wherein thememory controller is configured to store the preloaded data on thememory array in the reflow-protection mode as single-level cells (SLC)to reduce corruption of the preloaded data during assembly of theelectronic device including the memory device, and to store the receiveddata in the second mode on the memory array as multi-level cells (MLC).4. The memory device of claim 3, wherein, after the received dataexceeds the threshold amount, the memory controller is configured tostore the received data stored in the first mode as SLC to the memoryarray as MLC.
 5. The memory device of claim 2, wherein, because thethreshold amount is greater than the amount of preloaded data, thememory device is configured to store received data in thereflow-protection mode for a short time after assembly of the electronicdevice, then transition after assembly of the electronic device to thenormal-operation mode after the received data exceeds the thresholdamount, without receiving a separate indication from a host device ofcompleted assembly.
 6. The memory device of claim 2, wherein the memorycontroller is configured to receive the threshold amount from a hostdevice prior to receiving the preloaded data.
 7. The memory device ofclaim 2, wherein the memory controller is configured to transition fromthe first mode to the second mode without receiving a separateverification of preloaded data.
 8. The memory device of claim 1, whereinthe memory controller is configured to store received data on the memoryarray at a first level in the first mode, the first level having a firstmemory density, and wherein the memory controller is configured to storereceived data on the memory array at a second level in the second mode,the second level having a second memory density greater than the firstmemory density.
 9. The memory device of claim 1, wherein the memorycontroller is configured to perform background operations in the secondmode, and to suspend background operations in the first mode, whereinbackground operations include data migration, and wherein the thresholdamount is 5 gigabytes (GB) of data.
 10. The memory device of claim 1,wherein the memory controller is configured to transition from the firstmode to the second mode without receiving a separate indication ofcompleted assembly.
 11. A method for managing a memory device to reducecorruption of received data during assembly, the method comprising anumber of operations performed by a memory controller of a memory array,the memory array having groups of multiple blocks of memory cells, theoperations comprising: storing received data on the memory array in afirst mode having a first threshold temperature margin until thereceived data exceeds a threshold amount; and transitioning from thefirst mode to a second mode having a second threshold temperature marginafter the received data exceeds the threshold amount, wherein the secondthreshold temperature margin is less than the first thresholdtemperature margin.
 12. The method of claim 11, wherein storing receiveddata on the memory array in the first mode includes storing preloadeddata on the memory array in the first mode until the received dataexceeds the threshold amount, wherein the threshold amount is greaterthan the preloaded data, and wherein the first mode is areflow-protection mode and the second mode is a normal-operation mode.13. The method of claim 12, the operations comprising: writing receiveddata in the reflow-protection mode on the memory array as single-levelcells (SLC); and writing received data in the normal-operation mode onthe memory array as multi-level cells (MLC), wherein preloaded dataincludes a kernel and pre-loaded software for an electronic deviceconfigured to include the memory device, and wherein writing receiveddata in the reflow-protection mode as SLC includes to reduce corruptionof the preloaded data during assembly of the electronic device includingthe memory device.
 14. The method of claim 12, wherein transitioningfrom the reflow-protection mode to the normal-operation mode includeswriting the received data stored in the reflow-protection mode as SLC tothe memory array as MLC.
 15. A memory device configured to reducecorruption of received data during assembly, the memory devicecomprising: a memory array having groups of multiple blocks of memorycells; and a memory controller operably coupled to the memory array, thememory controller to perform operations comprising: store received dataon the memory array in a first mode having a first density until thereceived data exceeds a threshold amount; and transition from the firstmode to a second mode having a second density after the received dataexceeds the threshold amountwherein the second density is greater thanthe first density.
 16. The memory device of claim 15, wherein the memorycontroller is configured to store received data, including preloadeddata, on the memory array in the first mode until the received dataexceeds the threshold amount, wherein the threshold amount is greaterthan the preloaded data, and wherein the first mode is areflow-protection mode and the second mode is a normal-operation mode.17. The memory device of claim 16, wherein the memory controller isconfigured to store the preloaded data on the memory array in thereflow-protection mode as single-level cells (SLC) to reduce corruptionof the preloaded data during assembly of the electronic device includingthe memory device, and to store the received data in the second mode onthe memory array as multi-level cells (MLC).
 18. The memory device ofclaim 16, wherein, because the threshold amount is greater than theamount of preloaded data, the memory device is configured to storereceived data in the reflow-protection mode for a short time afterassembly of the electronic device, then transition after assembly of theelectronic device to the normal-operation mode after the received dataexceeds the threshold amount, without receiving a separate indicationfrom a host device of completed assembly.
 19. The memory device of claim16, wherein the memory controller is configured to transition from thefirst mode to the second mode without receiving a separate verificationof preloaded data.
 20. The memory device of claim 15, wherein the memorycontroller is configured to store received data on the memory array inthe first mode having a first threshold temperature margin, and in thesecond mode having a second threshold temperature margin, and whereinthe second threshold temperature margin is less than the first thresholdtemperature margin.
 21. The memory device of claim 15, wherein thememory controller is configured to perform background operations in thesecond mode, and to suspend background operations in the first mode,wherein background operations include data migration, and wherein thethreshold amount is 5 gigabytes (GB) of data.
 22. The memory device ofclaim 15, wherein the memory controller is configured to transition fromthe first mode to the second mode without receiving a separateindication of completed assembly.
 23. A method for managing a memorydevice to reduce corruption of received data during assembly, the methodcomprising a number of operations performed by a memory controller of amemory array, the memory array having groups of multiple blocks ofmemory cells, the operations comprising: storing received data on thememory array in a first e having a first density until the received dataexceeds a threshold amount; and transitioning from the first mode to asecond mode having a second density after the received data exceeds thethreshold amount wherein the second density is greater than the firstdensity.
 24. The method of claim 23, wherein storing received data onthe memory array in the first mode includes storing preloaded data onthe memory array in the first mode until the received data exceeds thethreshold amount, wherein the threshold amount is greater than thepreloaded data, and wherein the first mode is a reflow-protection modeand the second mode is a normal-operation mode.
 25. The method of claim24, the operations comprising: writing received data in thereflow-protection mode on the memory array as single-level cells (SLC)having a first threshold temperature margin; and writing received datain the normal-operation mode on the memory array as multi-level cells(MLC) second threshold temperature margin, wherein the second thresholdtemperature margin is less than the first threshold temperature margin,wherein preloaded data includes a kernel and pre-loaded software for anelectronic device configured to include the memory device, and whereinwriting received data in the reflow-protection mode as SLC includes toreduce corruption of the preloaded data during assembly of theelectronic device including the memory, device.